Head-mounted devices with display features are known in the art. Such head-mounted display devices (HMDs) include so-called ‘smart glasses’, which allow the wearer thereof to visualize information such as images or text for augmented reality.
Such devices raise issues of confidentiality of the information content displayed by the HMD. This is because persons other than the wearer may be in a position to view the information content displayed. Further, for aesthetic reasons, it is desirable that the HMD is designed in such a way that the display system is at least partially hidden from the view of an outside observer.
It is however required, for see-through HMDs, that the wearer still be able to view the ‘real’ world, so that the HMD should retain suitable transparency for see-through viewing by the wearer.